1. Field of the Invention
X-ray contrast media are involved for the visualization of extensive regions of the human body. The contrast agents have to have heavy atoms in high concentration to provide sufficient opacity in the concerned region. Because of the requirement of high concentrations in their use as contrast media, the presence of high proportions of heavy atoms, the desirability of water solubility, and the need for thermal and physiological stability, puts heavy restraints on the type of compounds which may be employed. In addition to the aforementioned restraints, there are concerns with viscosity, osmotic pressure, efficiency of synthesis, and the like.
Numerous iodinated compounds have been prepared for use as contrast media, but in each case, the compounds lack one or more desirable properties. There is, therefore, a continuing effort to develop compounds which provide the best combination of properties for contrast media.
2. Description of the Prior Art
U.S. Pat. No. 3,701,771 describes triiodobenzoyl sugar amines. Compounds which are presently commercially available include bis-3,5-diacetamido benzoate. (Iopamidol), N,N'-di(1',3'-dihydroxypropyl-2') 5-L-lactolylamido isophthaldiamide; and 3-acetamido-5-(N-methyl acetamido) benzoyl derivative of glucosamine. Sovak, et al., Radiology 117:717 (1975) describe di-iodo-triglucosyl benzene. Weitl, et al., J. Med. Chem. 19 353 (1976) describe 2,4,6-triiodo-3-acetamiodo-5-N-methylcarboxamidophenyl .beta.-D-glucopyranoside as a contrast medium. In the abstracts for the April ACS meeting (1979), is an abstract by Ranganathan and Sovak, entitled "Syntheses of carboxamido-triiodophenyl ethers of hexoses from nitroaromatics and their degradation into pentose derivatives."